Component packages typically comprise a die pad or heat sink which supports the component, for example, in the form of a semiconductor chip. The die pad or heat sink and components are encapsulated in a resin material. This is generally achieved by locating the die pad and components within a mold cavity, and injecting or introducing resin material into the mold cavity. By surrounding the die pad or heat sink with resin material, an isolation layer is formed on the rear surface of the die pad.
The problem with this known method is that the die pad or heat sink may move within the mold cavity during injection of the encapsulating material, and accordingly it becomes difficult to reproduce a highly accurate isolation layer thickness on the rear of the heat sink. To try and overcome this problem, it has been proposed to maintain the position of the die pad or heat sink within the mold cavity, for example, using one or more pins which hold the die pad or heat sink in position. In one example, the pins are retractable, such that these are removed during the molding process. However, such retractable pins are liable to wear, and therefore regularly need replacing. Further, the retraction of the pins must be carefully controlled to ensure that the encapsulating material fills the spaces from which the pins were retracted. The difficulty in accurately timing the retraction of the pins may result in a highly inconsistent outcome of the product. Where the pins are fixed, it is necessary to remove the pins after initial molding, and to then fill the hole left by the pins. Typically, the material used to fill these holes is not the same as the mold compound, leading to a possible material mismatch.